Spanish phrase
Por si ~.
Meaning
Just in case ___.
When to use it
Indicates doing something as a precaution. Common in casual speech when someone prepares or carries something to be ready for a possible outcome.
Example dialogue
Por si llueve, llevo mi paraguas.
Just in case it rains, I'll bring my umbrella.
Buena idea, yo también llevo uno.
Good idea, I'll bring one too.